Many hand-propelled wheelchairs are equipped with a pair of grip rings, or hand rims. Each grip ring is mounted outboard of a respective wheel of the wheelchair. A series of posts, or standoffs, extend between an inner side of the grip ring and an outer side of a rim portion of the wheel, and attach the grip ring to the wheel. Typically, grip rings are constructed of steel tubing or composite material tubing. The grip rings are used by the wheelchair operator to propel and maneuver the wheelchair.
Conventional grip rings have several disadvantages. Grip ring tubing typically has a relatively small diameter, which provides a limited gripping surface for a user. As a result, the user will experience difficulty propelling the wheelchair in certain situations, such as when traveling up ramps, traversing carpeted areas or traversing rough terrain. The limited gripping surface provided by the conventional grip ring also makes it difficult for the user to stop the wheelchair when descending declined surfaces or when traveling at high speeds.
The lack of sufficient gripping surface can cause the user to resort to improper and dangerous techniques to propel and maneuver the wheelchair. For example, the user may simultaneously grip both the wheel and the grip ring while propelling the wheelchair or the user may grip substantially the entire diameter of the grip ring while braking the wheelchair in order to obtain a greater gripping surface. Both of the aforementioned techniques can result in injury to the user, because the user may catch her fingers in the spokes of the wheel while attempting to propel the wheelchair, or she may catch her fingers in the standoffs while attempting to brake the wheelchair.
Furthermore, the conventional grip ring is generally uncomfortable to the user's hand. The small surface area of the grip ring, the combination of the shape of the grip ring and the hardness off the grip ring makes the grip ring uncomfortable to use.
Additionally, the conventional grip ring can become even more uncomfortable and dangerous to use under adverse conditions. For example, conventional grip rings are slippery when they are wet, and the steel surfaces of the grip ring can become uncomfortably hot or cold depending on the temperature of their environment.
Attempts have been made in the prior art to provide improved grip rings for wheelchairs. For example, U.S. Pat. No. 6,120,047 teaches a dual grip ring assembly including a large grip ring mounted on a wheel of a wheelchair and a small grip ring mounted to and disposed outboard of the large grip ring. The large grip ring includes a foam coating and the small grip ring is constructed of aluminum. The large grip ring and small grip ring are designed to be gripped together to propel the vehicle, thereby providing a relatively large gripping area. The small grip ring is designed to be gripped alone for braking the wheelchair. Although this invention may improve performance in maneuvering the wheelchair, it adds significantly to the cost and assembly time of the grip ring assembly. Additionally, people with small hands (such as women and children) or arthritic hands may find it difficult to grip the dual grip ring assembly. Furthermore, the dual grip ring assembly substantially increases the width of the wheelchair over conventional grip ring assemblies, thereby making it more difficult to maneuver the wheelchair through tight spaces. U.S. Pat. No. 6,276,705 B1 teaches a double-rimmed grip ring assembly for a wheelchair. The grip ring assembly includes a first rim, a second rim coaxially aligned within the first grip ring and a vinyl-coated concave trough connecting the first rim to a wheel of the wheelchair. This assembly provides a high-friction gripping surface, but is substantially more complicated and costly to manufacture than conventional grip ring assemblies. Also, as is the case with U.S. Pat. No. 6,120,047, people with small hands or arthritic hands may find it difficult to grip both rims of the grip ring assembly. U.S. Pat. No. 6,241,268 B 1 discloses a grip ring having a friction coating on its upper surface. This invention provides a high friction gripping surface, but does not improve the comfort or substantially increase the gripping area of the grip ring.
Therefore, a device that improves the performance, comfort and safety of the conventional grip ring is needed. More particularly, a device that improves the traction, gripping area and feel of the conventional grip ring, without significantly adding to the cost or complexity of the grip ring and without significantly increasing the width of the wheelchair, is needed.